The outspoken musician - widow of the band's late singer Kurt Cobain - was fuming over The Beatles star fronting a mini reunion with surviving Nirvana members Dave Grohl, Krist Novoselic and Pat Smear at the 12.12.12 benefit concert at Madison Square Garden last night.

Courtney slammed the collaboration, on new track 'Cut Me Some Slack', saying Paul's late band mate John Lennon would have been a more fitting person to perform with the grunge band.

She told website TMZ: ''Look, if John were alive it would be cool.''

Courtney, 48, added she was upset Krist and Dave had described the show as a Nirvana ''reunion'' as she feels Kurt was the heart and soul of the 'Smells Like Teen Spirit' band.

Paul, 70, had rehearsed with the Nirvana members - whose career with the band was cut short in 1994 when Kurt took his own life -

earlier this year when Dave was recording the soundtrack to his documentary film, 'Sound City', on which 'Cut Me Some Slack' appears.

Introducing the group at the Concert for Sandy Relief - which raised money for people in the Caribbean and US who were left stricken by Hurricane Sandy in October - Paul said: ''The penny finally dropped that I was in the middle of a Nirvana reunion.''